function dx=obv(t,x,ut,Q)
dx=zeros(2,1);
f=6;th=Q(1);Jn=2;

dx(1)=x(2)+1.5*f^0.5*(th-x(1))^0.5*sign(th-x(1));
dx(2)=1/Jn*ut+1.1*f*sign(th-x(1));